Catalytic, diluent preparation of poly ketone having unsaturated terminal group

ABSTRACT

Contacting carbon monoxide and at lease one α-olefin in a diluent comprising at least 50% by volume of an aprotic polar compound in the presence of a catalyst formed by contacting a palladium compound, the anion of an acid having a pKa less than 4 and a bidentate phosphorus ligand results in the production of novel polyketone polymers having unsaturated end groups.

This invention relates to novel alternating polymers of carbon monoxidewith one or more olefinically unsaturated compounds.

Polymers of carbon monoxide and one or more ethylenically unsaturatedhydrocarbons are well known. Such polymers contain carbonyl groups inthe polymer backbone and are known as polyketones. The polymers areuseful in part because at least a portion of the carbonyl groups can beconverted by conventional chemical reactions into other functionalgroups, e.g., conversion into polyamines by reaction with ammonia andconversion into polyols by catalytic hydrogenation. The polyketonepolymers independently have utility as will be described.

The carbon monoxide polymers produced by polymerization of carbonmonoxide and ethylenically unsaturated hydrocarbons such as ethylene aregenerally high molecular weight linear alternating polymers having oneunit of carbon monoxide per unit of hydrocarbon. The polymers aretypically produced employing a catalyst comprising certain Group VIIImetal compounds, e.g., a palladium compound, an anion of an acid with apKa less than 4, and a bidentate phosphorus ligand represented by theformula

    R.sup.1 R.sup.2 --P--R--P--R.sup.3 R.sup.4

wherein R¹, R², R³ and R⁴ independently are organic radicals, butpreferably are similar, and R is a bivalent organic bridging grouphaving at least two carbon atoms in the bridge. When the olefinicallyunsaturated hydrocarbon is ethylene, the polymers are inexpensive andprovide good mechanical properties of strength, stiffness and impactresistance.

The preparation of the polymers by using the above-described catalystcompositions may be carried out by contacting the monomers at anelevated temperature and pressure with a solution of the catalystcomposition in a protic polar diluent in which the polymers areinsoluble or virtually insoluble. During the polymerization, thepolymers are obtained in the form of a suspension in the diluent. Afterthe desired degree of polymerization is reached, the polymerization isgenerally terminated by cooling and releasing the pressure. The polymerscan be isolated from the suspension for instance by means of filtrationor centrifugation. Lower aliphatic alcohols, such as methanol have beenfound to be very suitable protic polar diluents.

The type of diluent used has an effect on the terminal groups occurringin the polymers. Thus, when carbon monoxide is polymerized with ethenein methanol as the diluent and by using the above-mentioned catalystcompositions, the resulting polymers will be substantially polymerswhich can be represented by the formula CH₃ --CH₂ --CO--(C₂ H₄--CO--)_(n) --CH₂ --CH₂ --CO--OCH₃, i.e. polymers whose moleculessubstantially bear an alkyl keto group at one end and an alkyl estergroup at the other end. With a view to the possible uses of thepolymers, it is desirable that either one of the terminal groups in atleast part of the polymer molecules should contain an olefinicallyunsaturated double bond, so that the polymers can be suitably used as acomponent in radical polymerization processes with olefinicallyunsaturated monomers or with olefinically unsaturated polymers.

The Applicant has determined that conversion of the alkyl ester groupswhich occur in the polymers as terminal groups into hydroxyl groups bymeans of catalytic hydrogenation followed by catalytic dehydration isnot a suitable route to the introduction of an olefinically unsaturateddouble bond into either one of the terminal groups of the polymermolecules. Owing to various side reactions, for instance thedeterioration of carbonyl groups present in the polymer molecules, thepolymer mixture formed will be one in which much of the linear characterof the polymers is lost, while the introduction of an olefinicallyunsaturated double bond into either of the two terminal groups of thepolymer molecules remains minimal.

SUMMARY OF THE INVENTION

The present invention includes certain novel polymers and a process ofproducing the polymers. More particularly, the polymers of the inventionare polymers of carbon monoxide and at least one α-olefin with at leasta portion of the polymer molecules having a carbon-carbon double bond ineither of the two terminal groups. The polymers are linear alternatingpolymers of carbon monoxide with the α-olefin, the polymers havingprimarily units of the type --CO--(A)-- wherein A is a polymer componentresulting from polymerization of the α-olefin. Polymer component Apreferably contains less than 10 carbon atoms and most preferablyethylene is used to produce the polymer.

The polymers of the invention are produced by contacting the monomers ina diluent consisting of more than 50% by volume of one or more aproticpolar compounds and in the presence of a catalyst comprising certainGroup VIII metal compounds, e.g., a palladium compound, an anion of anacid with a pKa less than 4, and a bidentate phosphorus ligandrepresented by the formula

    R.sup.1 R.sup.2 --P--R--P--R.sup.3 R.sup.4

wherein R¹, R², R³ and R⁴ independently are organic radicals, butpreferably are similar, and R is a bivalent organic bridging grouphaving at least two carbon atoms in the bridge. Preferred aprotic polarcompounds for providing the unsaturated terminal groups are dimethylsulfoxide and N-methyl-2-pyrrolidone. The polymerization of carbonmonoxide with ethylene in dimethyl sulphoxide as the diluent and usingcatalyst compositions as mentioned hereinbefore will lead to polymerswhich can be represented substantially by the following formula CH₃--CH₂ --CO--(C₂ H₄ --CO--)_(n) --CH₂ --CH₂ --CO--CH═CH₂, i.e. polymerswhose molecules substantially bear an alkyl keto group at one end and avinyl keto group at the other end.

Preferably, more than 25% of the polymer molecules, and in particularmore than 40% of the polymer molecules, of the polymers of the inventioncontain an olefinically unsaturated double bond in either of the twoterminal groups.

DESCRIPTION OF THE INVENTION

The polymers of the invention are linear alternating polymers of carbonmonoxide and at least one α-olefin with at least a portion of thepolymer molecules having a carbon-carbon double bond in either of thetwo terminal groups. The polymers are linear alternating polymers ofcarbon monoxide with the α-olefin, the polymers having primarily unitsof the type --CO--(A)-- wherein A is a polymer component resulting frompolymerization of the α-olefin.

The α-olefins employed to produce the units containing component A havefrom 2 to 20, but preferably 2 to 10, carbon atoms inclusive. Usefulα-olefins are ethylene, propylene, and 1-butene. Polymerization is mosteasily accomplished when a single α-olefin is employed and particularlyuseful is ethylene.

The process of the invention comprises contacting carbon monoxide andthe α-olefin in the presence of a catalyst composition formed bycontacting a palladium compound, an anion of an acid having a pKa(determined in aqueous solution at 18° C.) less than 4, preferably lessthan 2, and a bidentate phosphorus ligand represented by the formula

    R.sup.1 R.sup.2 --P--R--P--R.sup.3 R.sup.4

wherein R¹, R², R³ and R⁴ independently are organic radicals which mayor may not be aryl groups, but preferably are similar aryl groups, and Ris a bivalent organic bridging group having at least two carbon atoms inthe bridge.

The palladium compound employed in the catalyst compositions is apalladium salt and preferably a palladium carboxylate such as palladiumacetate. The anion is an anion of an acid having a pKa less than about4, such as mineral acids including perchloric acid, sulfuric acid,phosphoric acid, and nitrous acid, sulfonic acids includingmethanesulfonic acid, trifluoromethanesulfonic acid,2-hydroxypropane-2-sulfonic acid, and para-toluenesulfonic acid, andcarboxylic acids including trichloroacetic acid, dichloroacetic acid,trifluoroacetic acid, difluoroacetic acid, tartaric acid, and2,5-dihydroxybenzoic acid. Anions of acids having a pKa less than 2 areprefered and in particular anions of sulfonic acids or carboxylic acids,such as para-toluenesulfonic acid or trifluoroacetic acid, respectively.

The anion is present in the catalyst composition in an amount from about0.5 to about 200 equivalents per gram atom of palladium and preferablyfrom about 1 to about 100 equivalents per gram atom of palladium. Theanion is provided as the acid or as a salt of a non-noble transitionmetal such as zirconium, vanadium, chromium, iron, nickel, copper orzinc. When the anion is provided as the salt of a non-noble transitionmetal, a copper salt is prefered. Optionally, the palladium compound andthe anion of the acid can be supplied as a single compound such aspalladium para-tosylate, having the formula Pd(CH₃ CN)₂ (O₃ S--C₆ H₄--CH₃)₂, which is prepared by reaction of palladium chloride with thesilver salt of para-toluenesulfonic acid in acetonitrile as the solventor by reaction of palladium acetate and para-toluenesulfonic acid inacetonitrile as solvent.

In the phosphorus bidentate ligands having the formula R¹ R²--P--R--P--R³ R⁴ as described above, the preferred R group contains 3atoms in the bridge with at least two of the atoms being carbon atoms.Examples of suitable bridging groups R are the --CH₂ --CH₂ --CH₂ --group, the --CH₂ --C(CH₃)₂ --CH₂ -- group, the --CH₂ --Si(CH₃)₂ --CH₂ --group, and the --CH₂ --C(R₅)(R₆)--CH₂ -- group in which R₅ represents amethyl group and R₆ represents a diphenylphosphinomethyl group. A verysuitable phosphine ligand is 1,3-bis(diphenylphosphino)propane. Bypreference, the phosphorus bidentate ligands are used in a quantity fromabout 0.1 to about 3 mol per mol of palladium compound, preferably fromabout 0.75 mol to about 3 mol per mol of palladium compound.

The preparation of the polymers of the invention is carried out in adiluent which comprises more than 50% by volume of one or more aproticpolar compounds. Preferably, the diluent used comprises more than 75% byvolume of one or more aprotic polar compounds. Examples of suitableaprotic polar diluent are dimethyl sulfoxide, N-methyl-2-pyrrolidone,N,N-dimethyl acetamide, and an acetonitrile. Preferred aprotic polardiluents are dimethyl sulfoxide and N-methyl-2-pyrrolidone. In additionto one or more aprotic polar compounds, the diluent used may alsoinclude one or more other compounds. Examples of such compounds arealcohols, such as isopropanol, and ketones, such as acetone.

The catalyst composition useful in the process of the invention isemployed in quantities from about 1×10⁻⁷ mol to about 1×10⁻³ gram atomof palladium per mol of α-olefin are satisfactory with quantitiescontaining from about 1×10⁻⁶ to about 1×10⁻⁴ gram atom of palladium permol of the α-olefin being preferred. The molar ratio of the olefinicallyunsaturated compounds relative to carbon monoxide is preferably 10:1 to1:5 and most preferably 5:1 to 1:2.

The polymerization may be carried out either batchwise or continuous. Ina typical polymerization, conditions employed include reactiontemperatures from about 20° C. to about 200° C., preferably from about30° C. to about 150° C. Typical reaction pressures vary from about 1 toabout 200 bar, preferably from about 20 to about 100 bar. The carbonmonoxide used in the polymerization may contain contaminants such ashydrogen, carbon dioxide, and nitrogen. The mechanical form of thereactor is not critical provided it maintains the desired polymerizationconditions of temperature and pressure. Subsequent to polymerization,the terpolymer product is recovered by conventional means such asfiltration or decantation.

ILLUSTRATIVE EMBODIMENT I

A carbon monoxide/ethylene copolymer was prepared by charging to amagnetically stirred autoclave of 250 ml capacity, a catalystcomposition solution comprising 50 ml of dimethyl sulfoxide, 0.1 mmol ofpalladium acetate, 2 mmol of trifluoroacetic acid, and 0.15 mmol of1,3-bis(diphenylphosphino)propane. After evacuation of air present inthe autoclave, ethylene under pressure was added until a pressure of 20bar was reached. Then carbon monoxide was introduced under pressureuntil a total pressure of 50 bar was reached. The contents of theautoclave were heated and maintained at 80° C. After 5 hours thepolymerization was terminated by cooling to room temperature andreleasing pressure. The polymer was filtered, washed with methanol anddried in under vacuum at room temperature.

The polymerization rate was 160 grams of copolymer per gram of palladiumper hour. The copolymer contained unsaturated terminal groups at leastat one end in about 70% of the polymer molecules on the average.

ILLUSTRATIVE EMBODIMENT II

The procedure of Illustrative Embodiment I was repeated except that (a)the catalyst solution contained 50 ml of N-methyl-2-pyrrolidone and 5 mlof isopropyl alcohol instead of dimethyl sulfoxide, and (b) the reactiontime was 3 hours.

The polymerization rate was 460 grams of copolymer per gram of palladiumper hour. The copolymer contained unsaturated terminal groups at leastat one end in about 90% of the polymer molecules on the average.

ILLUSTRATIVE EMBODIMENT III

The procedure of Illustrative Embodiment I was repeated except that thecatalyst solution contained 50 ml of N-methyl-2-pyrrolidone instead ofdimethyl sulfoxide.

The polymerization rate was 360 grams of copolymer per gram of palladiumper hour. The copolymer contained unsaturated terminal groups at leastat one end in about 100% of the polymer molecules on the average.

ILLUSTRATIVE EMBODIMENT IV

The procedure of Illustrative Embodiment I was repeated except that (a)the catalyst solution contained 50 ml of N-methyl-2-pyrrolidone and 10ml of acetone instead of dimethyl sulfoxide, and (b) the reaction timewas 1 hour.

The polymerization rate was 740 grams of copolymer per gram of palladiumper hour. The copolymer contained unsaturated terminal groups at leastat one end in about 90% of the polymer molecules on the average.

ILLUSTRATIVE EMBODIMENT V

The procedure of Illustrative Embodiment I was repeated except that (a)the catalyst solution contained 50 ml of N-methyl-2-pyrrolidone and 5 mlof isopropyl alcohol instead of dimethyl sulfoxide, and 0.5 mmol ofpara-toluenesulfonic acid instead of trifluoroacetic acid, and (b) thereaction time was 2.5 hours.

The polymerization rate was 300 grams of copolymer per gram of palladiumper hour. The copolymer contained unsaturated terminal groups at leastat one end in about 50% of the polymer molecules on the average.

With the aid of ¹³ C-NMR analysis it was established that the copolymersprepared according to Illustrative Embodiments I-V had a linearstructure and were made up of the units --CO--(C₂ H₄)--. It was furtherestablished that the copolymers had the indicated amounts of unsaturatedterminal groups.

What is claimed is:
 1. The process of producing a linear, alternatingpolymer by polymerizing carbon monoxide and at least one α-olefin in adiluent that comprises more than 50% by volume of one or more compoundsselected from the group consisting of dimethyl sulfoxide,N-methyl-2-pyrrolidone, N,N-dimethyl acetamide or acetonitrile in thepresence of a catalyst composition formed by contacting a palladiumcompound, the anion of an acid having a pKa less than 4, and a bidentateligand of phosphorus.
 2. The process of claim 1 wherein carbon monoxideis polymerized with ethylene.
 3. The process of claim 1 wherein thebidentate ligand is a phosphorus bidentate ligand of the formula##STR1## wherein R¹, R², R³ and R⁴ independently are hydrocarbyl groups,and R has at least two carbon atoms in the phosphorus-phosphorus bridge.4. The process of claim 3 wherein the bidentate phosphorus ligand is1,3-bis(diphenylphosphino)propane.
 5. The process of claim 1 wherein theanion is an anion of an acid having a pKa less than
 2. 6. The process ofclaim 5 wherein the acid having a pKa less than 2 is trifluoroaceticacid.
 7. The process of claim 1 wherein the compound isN-methyl-2-pyrrolidone or dimethyl sulfoxide.
 8. The process of claim 1wherein the diluent comprises more than 75% by volume of the compound.9. The process of claim 3 wherein the diluent consists ofN-methyl-2-pyrrolidone.
 10. The process of claim 3 wherein the diluentconsists of dimethyl sulfoxide.